With the widespread use of network cameras and mass storages, systems for recording video images from many cameras are more often used in real situations. To deliver video data from a plurality of cameras to one place via a network, it is important to ensure that the sum of the encoding bit rates of video signals from all the cameras is below a maximum network bandwidth.
One proposed solution, which is a first related art for the present invention, is determining individual encoding bit rates for the respective cameras so that the sum of the encoding bit rates of video signals from all the cameras is below a predefined network bandwidth (refer to PTL 1, for example). In this first related art, which is a system where video images from cameras are displayed in the corresponding display windows on a display installed on the monitoring device, in order to determine encoding bit rates for the individual cameras, temporary encoding bit rates for individual cameras are determined based on their respective window sizes, then bit rate ratios allocated for the individual cameras are calculated based on the determined encoding bit rates, and then a predetermined network bandwidth is divided according to the allocated bit rate ratios for the individual cameras as calculated. Alternatively, temporary encoding bit rates for individual cameras are determined based on their respective display window sizes, then, if the sum of the temporary encoding bit rates as determined for higher priority cameras is below a predetermined network bandwidth, these temporary encoding bit rates are determined to be the encoding bit rates for the higher priority cameras, and encoding bit rates for other cameras are determined based on the remaining bandwidth.
Another proposed solution, which is a second related art for the present invention, is providing cameras with alarm functions so that the cameras are only permitted to transmit their video signals to a monitoring device via a network to be recorded during the period when an alarm state is detected (refer to PTL 2, for example).
Another proposed solution, which is a third related art for the present invention, is interpolating video frames into a moving image section of highly dynamic motion so as to play back in fluid motion, while reducing video frames in a section of less dynamic motion (refer to PTL 3, for example).